bytes_after_return
Returns the number of bytes remaining to be read in the
prop−
erty if a partial read was performed.

data
Specifies the property data.

display
Specifies the connection to the X server.

delete_property
Specifies a Boolean value that determines whether the
property
is to be deleted.

deviceid
The device to list the properties for.

format
Specifies whether the data should be viewed as a list of
8−bit, 16−bit, or 32−bit quantities.
Possible values are 8,
16, and 32. This information allows the X server to
correctly
perform byte−swap operations as necessary. If the
format is 16−bit or 32−bit, you must explicitly
cast your
data pointer to an (unsigned char *) in the call to
XIChangeProperty.

format_return
Returns the actual format of the property.

length
Specifies the length in 32−bit multiples of the data
to be
retrieved.

offset
Specifies the offset in the specified property (in
32−bit
quantities) where the data is to be retrieved.

mode
One of PropModeAppend, PropModePrepend or
PropModeReplace.

num_items
Number of items in data in the format specified.

nitems_return
Returns the actual number of 8−bit, 16−bit, or
32−bit items
stored in data.

property
Specifies the property name.

type
Specifies the type of the property. The X server does not
interpret the type but simply passes it back to an
application
that later calls XIGetProperty.

type_return
Returns the atom identifier that defines the actual type of
the property.

DESCRIPTION

The
XIGetProperty function returns the actual type of the
property; the actual format of the property; the number of
8−bit, 16−bit, or 32−bit items
transferred; the number of bytes remaining to be read in the
property; and a pointer to the data actually returned.
XIGetProperty sets the return arguments as follows:

• If the
specified property does not exist for the specified device,
XIGetProperty returns None to actual_type_return and the
value zero to actual_format_return and bytes_after_return.
The nitems_return argument is empty. In this case, the
delete argument is ignored.

• If the
specified property exists but its type does not match the
specified type, XIGetProperty returns the actual property
type to actual_type_return, the actual property format
(never zero) to actual_format_return, and the property
length in bytes (even if the actual_format_return is 16 or
32) to bytes_after_return. It also ignores the delete
argument. The nitems_return argument is empty.

• If the
specified property exists and either you assign
AnyPropertyType to the req_type argument or the specified
type matches the actual property type, XIGetProperty returns
the actual property type to actual_type_return and the
actual property format (never zero) to actual_format_return.
It also returns a value to bytes_after_return and
nitems_return, by defining the following values:

The returned
value starts at byte index I in the property (indexing from
zero), and its length in bytes is L. If the value for
long_offset causes L to be negative, a BadValue error
results. The value of bytes_after_return is A, giving the
number of trailing unread bytes in the stored property.

If the returned
format is 8, the returned data is represented as a char
array. If the returned format is 16, the returned data is
represented as a uint16_t array and should be cast to that
type to obtain the ele− ments. If the returned format
is 32, the returned data is represented as a uint32_t array
and should be cast to that type to obtain the elements.

XIGetProperty
always allocates one extra byte in prop_return (even if the
property is zero length) and sets it to zero so that simple
properties consisting of characters do not have to be copied
into yet another string before use.

If delete is
True and bytes_after_return is zero, XIGetProperty deletes
the property from the window and generates an
XIPropertyNotify event on the window.

The function
returns Success if it executes successfully. To free the
resulting data, use XFree.

XIGetProperty
can generate BadAtom, BadValue, and BadWindow errors.

The
XIChangeProperty function alters the property for the
specified device and causes the X server to generate a
XIPropertyNotify event for that device. XIChangeProperty
performs the following:

• If mode
is PropModeReplace, XIChangeProperty discards the previous
property value and stores the new data.

• If mode
is PropModePrepend or PropModeAppend, XChangeProperty
inserts the specified data before the beginning of the
existing data or onto the end of the existing data,
respectively. The type and format must match the existing
property value, or a BadMatch error results. If the property
is undefined, it is treated as defined with the correct type
and format with zero−length data.

If the
specified format is 8, the property data must be a char
array. If the specified format is 16, the property data must
be a uint16_t array. If the specified format is 32, the
property data must be a uint32_t array.

The lifetime of
a property is not tied to the storing client. Properties
remain until explicitly deleted, until the device is
removed, or until the server resets. The maximum size of a
property is server dependent and can vary dynamically
depending on the amount of memory the server has available.
(If there is insufficient space, a BadAlloc error
results.)

The
XIDeleteProperty function deletes the specified property
only if the property was defined on the specified device and
causes the X server to generate a XIPropertyNotify event for
the device unless the property does not exist.

XIDeleteProperty
can generate BadAtom and BadDevice errors.

DIAGNOSTICS

BadAlloc The
server failed to allocate the requested resource or server
memory.

BadAtom A value
for an Atom argument does not name a defined Atom.

BadValue Some
numeric value falls outside the range of values accepted by
the request. Unless a specific range is specified for an
argument, the full range defined by the argument’s
type is accepted. Any argument defined as a set of
alternatives can generate this error.

BadDevice An
invalid device was specified. The device does not exist.

BadAtom An
invalid property was specified. The property does not
exist.